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Evolution of interacting binaries with a B type primary at birth
We revisited the analytical expression for the mass ratio distributionfor non-evolved binaries with a B type primary. Selection effectsgoverning the observations were taken into account in order to comparetheory with observations. Theory was optimized so as to fit best withthe observed q-distribution of SB1s and SB2s. The accuracy of thistheoretical mass ratio distribution function is severely hindered by theuncertainties on the observations. We present a library of evolutionarycomputations for binaries with a B type primary at birth. Some liberalcomputations including loss of mass and angular momentum during binaryevolution are added to an extensive grid of conservative calculations.Our computations are compared statistically to the observeddistributions of orbital periods and mass ratios of Algols. ConservativeRoche Lobe Over Flow (RLOF) reproduces the observed distribution oforbital periods but fails to explain the observed mass ratios in therange q in [0.4-1]. In order to obtain a better fit the binaries have tolose a significant amount of matter, without losing much angularmomentum.
| A Spectroscopic Search for λ Bootis and Other Peculiar A-Type Stars in Intermediate-Age Open Clusters
As part of our continuing search for peculiar A-type stars, especiallyλ Bootis stars, in open clusters of all ages, we have obtainedclassification spectra of 130 late B, A, and early F-type stars in 12intermediate-age open clusters, including NGC 1039, 2281, 2548, 6633,7039, 7063, 7092, and 7209, IC 4665, IC 4756, Stock 2, and Praesepe. Thespectra were obtained with resolutions of 1.8 and 3.6 Å on the 0.8m telescope of Appalachian State University and were classified on theMK system. Numerous classical Ap and Am stars were found among the 130,including two new Ap stars in NGC 7092. In addition, three emission-linestars and two candidate λ Bootis stars were found. Neither ofthese λ Bootis candidates turned out to be members of theirrespective clusters. Combined with 184 stars previously classified in 10other intermediate-age open clusters, also devoid of λ Bootisstars, a statistically significant null result is obtained. We discussthe implications of this null result for our understanding of theλ Bootis mechanism.
| Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics
The Catalogue, available at the Centre de Données Stellaires deStrasbourg, consists of 13 573 records concerning the results obtainedfrom different methods for 7778 stars, reported in the literature. Thefollowing data are listed for each star: identifications, apparentmagnitude, spectral type, apparent diameter in arcsec, absolute radiusin solar units, method of determination, reference, remarks. Commentsand statistics obtained from CADARS are given. The Catalogue isavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcar?J/A+A/367/521
| X-Ray Activity in the Open Cluster IC 4665
We present the results of a joint ROSAT High Resolution Imager (HRI) andoptical investigation of the open cluster IC 4665. The ROSAT datacontains detections for 28 stellar sources in the field, including 22cluster members and candidate members spanning the color range -0.18<= (B-V)0 <= 1.63 (~B3-M3). Upper limits are given for theremaining members (or candidate members) in the HRI field. Keck HIRESspectra have been obtained that yield radial and rotational velocitymeasures, respectively, for faint, low-mass candidate members locatedwithin the field of the ROSAT HRI observation. In addition, photometryof possible optical counterparts to previously uncataloged X-ray sourcesin the HRI field is presented. The trends in X-ray properties with B-Vcolor in IC 4665 are found to be quite similar to that for other, morenearby young clusters such as the Pleiades and alpha Persei. Inparticular a maximum in normalized X-ray luminosity of log (LX/Lbol) ~=-3 is observed, beginning in the color range of (B-V)0 = 0.7-0.8. Thisis similar to the corresponding color range among Pleiades members, inagreement with the earlier estimate by Prosser & Giampapa that theage of IC 4665 is similar to the age of the Pleiades. The correlation ofrotation and X-ray emission levels is consistent with that in otheryoung clusters. Among the high-mass stars in IC 4665, five B stars aredetected as X-ray sources. Of these, one is a spectroscopic binary whilethe remaining objects are apparently single stars. The level ofintrinsic X-ray emission observed in the rapidly rotating (v sin i >200 km s-1), single B stars is consistent with an origin due to shockheating of the ambient medium by radiatively driven, rotationallyenhanced winds. On the basis of these observations and the results forother clusters, we argue that observed levels of X-ray emission inhigh-mass stars of log (LX/Lbol) > -6.0 are likely due to intrinsicemission associated with the B star itself rather than emission from alate-type secondary. Finally, our results suggest that the initialangular momentum distributions and the subsequent evolution of rotation,LX, and (LX/Lbol) occur in practically identical fashions in clusterswith ages <~100 Myr.
| Spectrophotometry of 237 Stars in 7 Open Clusters
Spectrophotometry is presented for 237 stars in 7 nearby open clusters:Hyades, Pleiades, Alpha Persei, Praesepe, Coma Berenices, IC 4665, andM39. The observations were taken by Lee McDonald and David Bursteinusing the Wampler single-channel scanner on the Crossley 0.9m telescopeat Lick Observatory from July 1973 through December 1974. Sixteenbandpasses spanning the spectral range 3500 Angstroms to 7780 Angstromswere observed for each star, with bandwidths 32Angstroms, 48 Angstromsor 64 Angstroms. Data are standardized to the Hayes-Latham system tomutual accuracy of 0.016 mag per passband. The accuracy of thespectrophotometry is assessed in three ways on a star-by-star basis.First, comparisons are made with previously published spectrophotometryfor 19 stars observed in common. Second, (B-V) colors and uvby colorsare compared for 236 stars and 221 stars, respectively. Finally,comparsions are made for 200 main sequence stars to the spectralsynthesis models of Kurucz, fixing log g = 4.0 and [Fe/H] = 0.0, andonly varying effective temperature. The accuracy of tests using uvbycolors and the Kurucz models are shown to track each other closely,yielding an accuracy estimate (1 sigma ) of 0.01 mag for the 13 colorsformed from bandpasses longward of the Balmer jump, and 0.02 mag for the3 colors formed from the three bandpasses below the Balmer jump. Incontrast, larger scatter is found relative to the previously publishedspectrophotometry of Bohm-Vitense & Johnson (16 stars in common) andGunn & Stryker (3 stars). We also show that the scatter in the fitsof the spectrophotometric colors and the uvby filter colors is areasonable way to identify the observations of which specific stars areaccurate to 1 sigma , 2 sigma , .... As such, the residuals from boththe filter color fits and the Kurucz model fits are tabulated for eachstar where it was possible to make a comparison, so users of these datacan choose stars according to the accuracy of the data that isappropriate to their needs. The very good agreement between the modelsand these data verifies the accuracy of these data, and also verifiesthe usefulness of the Kurucz models to define spectrophotometry forstars in this temperature range (>5000 K). These data define accuratespectrophotometry of bright, open cluster stars that can be used as asecondary flux calibration for CCD-based spectrophotometric surveys.
| UBV (RI)c observations of Johnson's standard sequence in IC 4665.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996MNRAS.282..313M&db_key=AST
| The λ 3984 feature in late-B spectroscopic binaries.
We report about a spectroscopic study aimed at searching the line Hg IIλ 3984 in a sample of 28 spectroscopic binaries with primaries inthe same temperature range as HgMn stars. One system, HD 75642, showsthis line very prominently. In another system, HD 41040, Hg may besomewhat overabundant, while HD 87751 shows marginal Mn and Penhancement. The present study does not bring a definitive answer to thequestion of the relation between binarity, slow rotation, and theappearance of HgMn anomalies in late B stars, possibly because othereffects (like the influence of a magnetic field), which could not betaken into consideration, are important too. In the course of thisstudy, 11 new double-lined spectroscopic binaries were discovered, 10 ofwhich were previously known as single-lined systems. Of particularinterest among them are 4 stars that may have the Si or He weakpeculiarities.
| New Variable in Ophiuchus
Not Available
| Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
| A new list of effective temperatures of chemically peculiar stars. II.
Not Available
| A search for radio emission from the 'nonmagnetic' chemically peculiar stars
We have observed 23 members of the Am and HgMn subclasses of chemicallypeculiar (CP) stars with the Very Large Array (VLA) to search fornonthermal radio emission at levels comparable to those found for the Siand He peculiar subclasses of the CP stars by Linsky et al. (1992). Thisstudy was motivated by recent claims that magnetic fields of kilogaussstrength are present in at least some of the Am and HgMn stars, contraryto previous beliefs, which would indicate that radio-emittingmagnetospheres could be present in these stars. We detected none of theAm and HgMn stars as radio emitters with upper limits typically lessthan 0.20 mJy. Applying a correlation between radio luminosity, surfacemagnetic field, and effective temperature derived from previous radiostudies of the Si and He peculiar CP stars, we find that the predictedradio luminosities of alpha And (an HgMn star) and Sirius (a hot Amstar) are more than an order of magnitude larger than the observed upperlimits, indicating that these stars lack magnetospheres, and, byinference, surface magnetic fields.
| ICCD speckle observations of binary stars. IX - A duplicity survey of the Pleiades, Praesepe, and IC 4665 clusters
Multiplicity of stars within clusters is a well-studied phenomenon.However, recent survey work done on the Hyades by Mason et al. (1993)would seem to indicate that even in the most often studied clusters,there may be binaries yet undiscovered. In order to expand the sample ofcluster binaries with potentially short-period visual orbits, a specklesurvey of 45 Pleiades, 54 Praesepe, and 22 IC 4665 bright stars (V isless than 10) for possible multiplicity was conducted at the KPNO 4 mMayall telescope between 1987 October and 1991 November. Of these, threenew binaries have been discovered: one in the Pleiades where the newcomponent may be spectroscopic, another in Praesepe which has beenconfirmed from examinations of archival observations and also has beenresolved by occultation, and the third in IC 4665. Continued study ofthese new binary stars could further refine the cluster distance modulias well as the cluster mass-luminosity relations.
| The open cluster IC 4665
The results of a combined astrometric, photometric, and spectroscopicprogram to identify members of the open cluster IC 4665 are presented.Numerous new proper motion/photometric candidate members and at least 23M dwarfs with H-alpha emission have been identified. A reanalysis of IC4665 age using different methods yields conflicting results ranging fromabout 3 X 10 exp 7 yr to the age of the Pleiades. This study provides alist of candidate cluster members in the intermediate and low-massregime of this cluster. Future spectroscopic observations of thesecandidates should eventually identify true cluster members.
| Liste des étoiles Ap et Am dans les amas ouverts (édition révisée)
Not Available
| Reinvestigation of the binary frequency in the open cluster IC 4665
The radial velocities of 15 bright B3-A2 stars in the cluster IC 4665are measured using a CCD. Only four of the 15 stars are spectroscopicbinaries, giving a binary frequency of 27 percent. Four of the sixsharp-lined stars are binaries, and none of the more rapidly rotatingstars are binaries with K at least 10 km/s. Statistically, nearly all ofthe stars with low projected rotational velocities are slow rotators,and most are binaries; two of the four binaries may rotatesynchronously. In two of the four binaries, the mass ratios are near1.0, as would be expected for binary formation in three-bodyinteractions after many crossing times. The measured cluster velcoitydispersion is only 1.6 km/s, but most of that is still probably due tomeasuring errors.
| Observations that link infrared cirrus and ultraviolet extinction
Results are presented of UV extinction measurements of 17 stars in theopen cluster IC 4665 and of four stars in the open cluster NGC 1647,showing that the UV extinctions of the two clusters stars have differentproperties. Whereas the stars in NGC 1647 cluster are typical of generalinterstellar space, the stars in IC 4665 have a small 'linear' termwhich is typical of stars found near regions of active star formation.Using data from the IRAS satellite to study the emission by the'infrared cirrus' for each of the regions and to measure theI(60-micron)/I(100-micron) ratio for the two regions, it was found that,when the linear term component is present, it dominates the 100-microncirrus emission. When it is absent, the 100-micron emission is from therelatively hot particles that are responsible for the 60-micronemission. It is suggested that the 60-micron emitters are smallcarbonaceous grains that are major contributors to all parts of the UVextinction except the linear term.
| Early type high-velocity stars in the solar neighborhood. IV - Four-color and H-beta photometry
Results are presented from photometric obaservations in the Stromgrenuvby four-color and H-beta systems of early-type high-velocity stars inthe solar neighborhood. Several types of photometrically peculiar starsare selected on the basis of their Stromgren indices and areprovisionally identified as peculiar A stars, field horizontal-branchstars, metal-poor stars near the Population II and old-disk turnoffs,metal-poor blue stragglers, or metallic-line A stars. Numerousphotometrically normal stars were also found.
| Broad-band photometry of selected southern ultraviolet-bright stars.
Not Available
| Close binaries observed polarimetrically
Not Available
| Liste des étoiles Ap et Am dans les amas ouverts (Edition révisée)
Not Available
| The discovery of a co-rotating magnetosphere in a helium weak star: HD5737 = alpha Scl
The discovery, using combined IUE spectroscopy and Zeeman polarimetricmagnetic field measurements, of a magnetosphere in a helium weak star isreported. The star, HD 5737 = alpha Scl, is one of the extreme He weakstars in its He deficiency, but is otherwise quite similar to the othersn stars HD 21699 and HD 79158. A period for the magnetic and C IV andSi IV variations of 21.65 days, a factor of 10 longer than the othervariable sn stars is indicated. The effective (longitudinal) field nullscorrespond extremely well to C IV line strength maxima. The magneticfield and equatorial magnetosphere are highly oblique (70 deg) and theline variations appear to be stable.
| Merged log of IUE observations.
Not Available
| Chemically peculiar stars in open clusters. I - The catalog
The largest existing compilation is presented of Ap and Am open clusterstars. The catalog contains information on 381 chemically peculiar (CP)stars of the upper main sequence in 79 open clusters. The catalog iscomposed of the following tables: (1) the main body, which lists CP (orsuspected CP) stars which are kinematical (or suspected kinematical)members of open clusters; (2) the list of CP (or suspected CP) starssometimes numbered among cluster members but which are actuallykinematical nonmembers; (3) the list of stars sometimes designated as'peculiar' but, in fact, probably not CP; (4) references for numberingsystems of cluster stars; (5) references for membership; and (6)references for spectral and/or peculiarity types.
| Catalog of AP and AM stars in open clusters
The previous results of Raab (1922), Markarian (1951), and Collinder(1931) have been used to catalog Ap and Am stars that are in the fieldof open clusters. Tabular data are presented for the clusterdesignation, the HD or HDE number, the right ascension (1900), thedeclination (1900), and the magnitude. Also listed are the spectraltypes and, for certain stars, the probability of cluster membership.
| Statistical Investigation of Chemically Peculiar Stars - Part Five - Spectroscopic Binary Stars
Not Available
| Statistical Investigation of Chemically Peculiar Stars - Part Four - Luminosity of Different Type Stars
Not Available
| On the Effective Temperatures of Chemically Peculiar Stars
Not Available
| Observational problems of investigation of stars with anomalous helium lines.
Not Available
| Galactic cluster star radial velocities obtained with a focal reducer field spectrograph. I - The clusters IC 1805, NGC 2287, NGC 2548, IC 4665, NGC 6633, NGC 6940 and NGC 7092
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1985A&AS...62..301G&db_key=AST
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Observation and Astrometry data
| Constellation: | Ophiucus |
| Right ascension: | 17h45m33.66s |
| Declination: | +05°42'56.5" |
| Apparent magnitude: | 7.695 |
| Proper motion RA: | 2.4 |
| Proper motion Dec: | -8.9 |
| B-T magnitude: | 7.693 |
| V-T magnitude: | 7.695 |
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